The invention relates to explosive devices, e.g., actuators, squibs, and detonators, to actuate a valve, drive a piston to rupture a conduit or to impact against an explosive to effect detonation or the like, etc.
Prior art explosive devices which are activated by electrical bridge-wires generally require a separate initiation material sensitive enough to be initiated by the electrical bridgewire, which initiation material then ignites and additional output charge material. Generally the initiation materials are less stable, more sensitive primary explosives and the output charge materials are more stable, less sensitive secondary explosives. These initiating materials present safety disadvantages in that they are generally spark sensitive and may be ignited by lightning strokes, accidental shock, and the like. For example, static electricity generated on the body of a person working on or with the device may accidentally set off those devices which use these initiating explosives. As such, extreme care and caution must be employed in handling these materials, not only from the standpoint of accidentally setting them off when placed in position for detonation, but also from the standpoint that the initiator material may accidentally ignite during fabrication of actuators, squibs or the like.
There are some materials that are directly ignitible by an electrical bridgewire, such as titanium-potassium perchlorate (Ti-KClO.sub.4) which is generally considered to be spark insensitive in a compacted or pressed condition, but which as a powder is spark sensitive. Therefore, devices employing that material may be erroneously believed to be static insensitive but may have deteriorated in use to a static sensitive condition by vibration, aging, and the like.
It would be preferred not to employ a spark or static sensitive material or a material which may become spark or static sensitive in or for squibs, actuators, or the like, or in their fabrication, because of the safety hazard of ignition from static electricity.
Although prior actuators, squibs and the like have been designed to be non-static sensitive by the incorporation of bleeder resistors, spark gaps, insulating sleeves, etc., these are not deemed completely safe as long as they are constructed of, or employ, explosive materials that are static sensitive. The above techniques are subject to manufacturing variables and unless all the materials of the device are static insensitive, the device will not be deemed completely safe from the static sensitivity standpoint.